I thought i'd solved it, but turns out it was never actually his catchphrase and it belonged to John Fashanu and Akabusi is pissed. Here's an extract from an article I found during my research.
Kriss Akabusi has stated he is to launch legal action giving him the right to strike anyone who wrongly claims he said ‘Awooga!’
Olympic Gold medallist, Akabusi, has said he has had enough of people stopping him in the street and shouting, “Awooga!” in his face. “It was alright at first, but enough is enough now,” said the former Record Breakers presenter.
The word has wrongly been attributed to Akabusi after a number of comedic stories that were circulated on the internet a decade ago. In these stories, Akabusi sexually pleasures a plethora of women in comedic circumstances.
The stories have achieved cult status and always sign off with the line, “he whispered ‘Awooga’ before patting her on the fanny.”